pinctrl: qcom: ssbi-gpio: fix gpio-hog related boot issues

When attempting to setup up a gpio hog, device probing will repeatedly
fail with -EPROBE_DEFERED errors. It is caused by a circular dependency
between the gpio and pinctrl frameworks. If the gpio-ranges property is
present in device tree, then the gpio framework will handle the gpio pin
registration and eliminate the circular dependency.

See Christian Lamparter's commit a86caa9ba5d7 ("pinctrl: msm: fix
gpio-hog related boot issues") for a detailed commit message that
explains the issue in much more detail. The code comment in this commit
came from Christian's commit.

I did not test this change against any hardware supported by this
particular driver, however I was able to validate this same fix works
for pinctrl-spmi-gpio.c using a LG Nexus 5 (hammerhead) phone.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
index 6b30bef829ab586c183f680fb90b1a42761f8a96..ded7d765af2e1fe8aefc72670917f115455bd6c1 100644 (file)
--- a/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
+++ b/drivers/pinctrl/qcom/pinctrl-ssbi-gpio.c
@@ -762,12 +762,23 @@ static int pm8xxx_gpio_probe(struct platform_device *pdev)
                return ret;
        }
 
-       ret = gpiochip_add_pin_range(&pctrl->chip,
-                                    dev_name(pctrl->dev),
-                                    0, 0, pctrl->chip.ngpio);
-       if (ret) {
-               dev_err(pctrl->dev, "failed to add pin range\n");
-               goto unregister_gpiochip;
+       /*
+        * For DeviceTree-supported systems, the gpio core checks the
+        * pinctrl's device node for the "gpio-ranges" property.
+        * If it is present, it takes care of adding the pin ranges
+        * for the driver. In this case the driver can skip ahead.
+        *
+        * In order to remain compatible with older, existing DeviceTree
+        * files which don't set the "gpio-ranges" property or systems that
+        * utilize ACPI the driver has to call gpiochip_add_pin_range().
+        */
+       if (!of_property_read_bool(pctrl->dev->of_node, "gpio-ranges")) {
+               ret = gpiochip_add_pin_range(&pctrl->chip, dev_name(pctrl->dev),
+                                            0, 0, pctrl->chip.ngpio);
+               if (ret) {
+                       dev_err(pctrl->dev, "failed to add pin range\n");
+                       goto unregister_gpiochip;
+               }
        }
 
        platform_set_drvdata(pdev, pctrl);